(1) Field of the Invention
This invention relates to heat dissipation of light-emitting diode (LED) lamps.
(2) Brief Description of Related Art
The high power LED light devices produce considerable amount of heat, which may cause performance degrade or even damage if the heat is not removed from the LED chips efficiently. In an LED light device, the core is an LED chip mounted on a substrate. A transparent top covering the LED chip serves as a lens for modifying the direction of the emitted light. Although there are many different designs, the major heat dissipation route for the heat produced by the LED chip usually is managed through the base substrate to which the LED chip is mounted or through an additional metal heat sink below the base substrate and then to the outer heat sink.
Traditional adoption of fans for active cooling system not only introduces noise problems but also brings risk of damage to a LED lamp if the fan is out of order. In contrast, passive cooling with natural convection is quiet, continuous and time-unlimited. But since a natural convection system is relatively weak for heat dissipation, to solve this problem, a large surface area is needed to enhance heat dissipation capacity. Most passive cooling devices for LED lamps adopt high-conductivity materials, such as copper or aluminum, with extended surfaces for heat dissipation. However, the thermal dissipation capacities of these pure metals may be still insufficient for dissipating the heat generated from the LED lamps which give a relatively high temperature during operation as a result. Therefore, highly conductive devices such as heat pipes or loop heat pipes have been applied in LED devices to replace the use of pure metal plates. U.S. Pat. No. 7,095,110 disclosed connecting LED chips with planar heat pipes to improve passive heat dissipation. However, additional heat dissipation devices such as extension surfaces or fins, which are important for passive natural convection, were not included.